In recent years, rechargeable batteries have been increasingly employed in target applications ranging from laptop computers, smartphones, and other low power battery applications, to electrical grid, backup power, and other high power battery applications. For example, such rechargeable batteries can include rechargeable battery cells such as nickel-metal-hydride (NiMH) battery cells, lithium-ion (Li-ion) battery cells, etc. One or more such NiMH or Li-ion battery cells can be included in a battery module, which can further include a battery manager. Such a battery module can be employed in a stand-alone application, or a plurality of such battery modules can be connected in series for use in applications that require increased battery voltages.
When such NiMH or Li-ion battery cells have been discharged below a minimum voltage level needed for operation (also referred to herein as the “under voltage protection (UVP) voltage level”), the battery cells typically must be pre-charged at a low current before they can receive a full-charge current at a higher value. Various circuit configurations are known for providing a pre-charge current to one or more NiMH or Li-ion battery cells included in a battery module. However, there is a need for more reliable systems and methods of pre-charging battery cells such as NiMH or Li-ion battery cells that are included in a plurality of series-connected battery modules.